welcome screen: populate example combobox

When an example is selected, help and the project are opened
in a split view. We try to read the xml file provided for
QtDemo to extract details about the examples provided. Will
try all available Qts, starting with the default version. Will
fail gracefully (provide a message and disable controls) if
examples or demos cannot be found. Will work if help is not
found, but show an error.

src/plugins/qt4projectmanager/qtversionmanager.h

@@ -86,10 +86,20 @@ public:
 
     bool hasDebuggingHelper() const;
     QString debuggingHelperLibrary() const;
+
     // Builds a debugging library
     // returns the output of the commands
     QString buildDebuggingHelperLibrary();
 
+    bool hasExamples() const;
+    QString examplesPath() const;
+
+    bool hasDocumentation() const;
+    QString documentationPath() const;
+
+    bool hasDemos() const;
+    QString demosPath() const;
+
     int uniqueId() const;
     bool isMSVC64Bit() const;
 
@@ -130,6 +140,9 @@ private:
     mutable bool m_notInstalled;
     mutable bool m_defaultConfigIsDebug;
     mutable bool m_defaultConfigIsDebugAndRelease;
+    mutable bool m_hasExamples;
+    mutable bool m_hasDemos;
+    mutable bool m_hasDocumentation;
 
     mutable QString m_qmakeCommand;
     mutable QString m_qtVersionString;
@@ -170,6 +183,7 @@ public:
 signals:
     void defaultQtVersionChanged();
     void qtVersionsChanged();
+    void updatedExamples(const QString& examplesPath, const QString& demosPath, const QString& docPath);
 private:
     // Used by QtOptionsPage
     void setNewQtVersions(QList<QtVersion *> newVersions, int newDefaultVersion);
@@ -179,6 +193,7 @@ private:
     void addNewVersionsFromInstaller();
     void updateSystemVersion();
     void updateDocumentation();
+    void updateExamples();
 
     static int indexOfVersionInList(const QtVersion * const version, const QList<QtVersion *> &list);
     void updateUniqueIdToIndexMap();